Mounting structure for electromagnetic contactor



Nov. 17, 1964 R. c. GUTBERLET MOUNTING STRUCTURE FOR ELECTROMAGNETIC CONTACTOR e Sheet-Sheet 1 Filed Aug. 30, 1961 IILI MOUNTING STRUCTURE FOR ELECTROMAGNETIC CONTACTOR 6 Sheets-Sheet 2 Filed Aug. 30, 1961 mww Nov. 17, 1964 R. c. GUTBERLET 3,157,765

MOUNTING STRUCTURE FOR ELECTROMAGNETIC CONTACTOR 6 Sheets-Sheet 3 Filed Aug. 30, 1961 Nov. 17, 1964 R. c. GUTBERLET 3,157,755

MOUNTING STRUCTURE FOR ELECTROMAGNETIC CONTACTOR Filed Aug 30, 1961 6 Sheets-Sheet 4 Nov. 17, 1964 R. c. GUTBERLET 3,157,765

MOUNTING STRUCTURE FOR ELECTROMAGNETIC CONTACTOR Filed Aug. 30, 1961 6 Sheets-Sheet 5 u '1 m "u 0 Q 1: r: w 18 3 s m a 52 f w l. a v,

III,

Nov. 17, 1964 R. c. GUTBERLET 3,157,765

MOUNTING STRUCTURE FOR ELECTROMAGNETIC CONTACTOR Filed Aug. so, 1961 6 Sheets-Sheet e United States Patent 3,157,765 MOUNTING STRUCTURE FGR ELECTRQ- MAGNETIQ GNTATGR Robert C. Gutberlet, Milwaukee, Wis, assignor to Gutier- Hanrrner, Inc, Milwaukee, Win, a corporation of Delaware Filed Aug. 30, 1961, Ser. No. 134,943 7 Claims. (Ci. zeta-s7) This invention relates to electric switches and more particularly to improvements in electric switch structures adapted for controlling large values of electric energy.

While not limited thereto, the invention is especially applicable to electromagnetic contactors or the like to improve the construction thereof and to facilitate adjustment and repair thereof. I

An object of the invention is to provide an improved electric switch.

A more specific object of the invention is to provide an electromagnetic contactor of improved construction affording ready removal of portions thereof for repair or replacement without detaching the contactor from its supporting structure.

Another specific object of the invention is to provide an electromagnetic switch of the type having arcing contacts and current carrying contacts with improved means for adjusting the contact pressures thereof.

Another specific object of the invention is to provide an electromagnetic actuator of the type having an elongated armature pivot with sealing means to prevent entry of deleterious material in the pivot.

Another specific object of the invention is to provide an electromagnetic actuator with improved means for retaining the coil on the core to prevent movement of the coil and to afford ready removal thereof.

Other objects and advantages of the invention will hereinafter appear.

The above mentioned and other objects and advantages of the invention and the manner of obtaining them will best be understood by reference to the following detailed description of an exemplary embodiment of an electric switch structure taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a front elevation view of an electrical contactor constructed in accordance with the invention;

FIG. 2 is a right side elevation view of the contactor of FIG. 1;

FIG. 3 is a cross-sectional view taken along line 33 of FIG. 1;

FIG. 4 is an exploded view of a portion of the contactor of FIG. 1;

FIG. 5 is an exploded view of another portion of the contactor of FIG. 1;

FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. 1;

FIG. 7 is a cross-sectional view of one side portion of the contactor taken along line 7-7 of FIG. 2;

FIG. 8 is a cross-sectional view of the portion of FIG. 7 taken along line 88 of FIG. 2;

FIG. 9 is a cross-sectional view of the potion of FIG. 7 taken along line 9-9 of FIG. 2;

FIG. 10 is an isometric view of a member constituting one-half of an arc shield showing the interior structure thereof; and

FIG. 11 is an isometric view of the member of FIG. 10 viewed from another direction.

Referring to FIGS. 1 and 2, there is shown a mounting panel or base 2 of electrically insulating material for supporting the contactor, the parts of the contactor being secured to the front surface as shown in FIG. 1 and to the left-hand surface of the panel as shown in FIG. 2 by bolts and screws extending into and through the panel.

The contactor is provided with an electroniagnet comprising a coil 4 having terminals 4a and 4b and a core 6 of magnetic material extending therethrough and rigidly secured to panel 2 and a pivotal armature a of magnetic material. The electromagnet is provided with means ac cessible from the front of panel 2 to afford ready removal of coil 4. This means comprises a washer 6a of larger diameter than the axial hole in the coil for maintaining the coil on the core, a screw 6b or the like threaded into an axial tapped hole in the free end of the core for retaining washer 6a in place and a slightly concave or dish-shaped relatively fiat resilient spring Washer 6c interposed between washer 6a and coil 4 with the concave side thereof toward the coil for pressing the coil against its supporting bracket hereinafter described.

An L-shaped bracket it) has the face of one angular portion Ilia arranged in parallel abutting relation to the lower portion of the front surface of panel 2 and another angular portion lilb extending horizontally from the lower edge of the panel. A screw 12 extends through a suitable hole in base 2 and a corresponding hole 10c (FIG. 4) in angular portion Illa into threaded engagement in an axial tapped hole in the other end of core 6 to rigidly secure the core and bracket to the panel. Another screw 14 (FIG. 2) offset from screw 12 extends through a suitable hole in panel 2 into threaded engagement in a tapped hole lild (FIG. 4) in angular portion 10a to prevent rotation of bracket 1% on screw 12.

As shown in FIGS. 2, 3 and 4, angular portion 19b of bracket 10 is provided with means affording a pivotal seat for armature 8 comprising a transverse bar 16 rigidly secured, as by Welding, across the upper surface thereof. Bar 16 is of rectangular cross-section or the like. One side of bar 16 forms with angular portion Mb a substantial right angle which provides a pivotal support for arma ture S. Angular portion 10b of bracket 10 is also provided with means for supporting resilient return means for the armature comprising a pair of spaced apart, parallel, upstanding bolts 1%, FIG. 4, extending therethrough a predetermined distance from bar 16 for maintaining and biasing the lower end of armature 8 in its pivot as hereinafter more fully described. A switch 2% shown in FIGS. 2 and 3 is mounted on the upper surface of the extreme end of angular portion lllb of bracket 10 for use in electrical interlocking or auxiliary circuits or the like.

As shown in FIGS. 2, 3 and 4, armature 8 is of generally flat configuration and is provided across its lower edge with an acute angular portion forming an elongated sharp edge So for pivoting in the substantially right angle between bar 1% and portion ltlb of the bracket. This long pivot edge prevents wear at the armature pivot. Armature 8 is confined against lateral movement by a pair of pins 16a extending from bar 16 on opposite sides of the lower end of the armature. A dust seal 16b of resilient or foam like rubber material is cemented along the upper surface of bar 16. Seal 161) has its edge pressed into engagement with the right-hand surface of armature 8 to seal the armature pivot from admission of dust or the like. A projection or plate 811 extends horizontally at a substantially right angle from the face of armature 8 adjacent the lower end thereof and is provided with a pair of enlarged, spaced holes for freely accommodating bolts 18 when the armature pivots. Holes 80 are provided with counter bores as shown in FIG. 4 for accommodating resilient armature return means such as the lower ends of helical compression springs 22 surrounding the respective bolts. The upper ends of springs 22 are stopped against suitable washers 18a which are held in place by nuts 18b threaded on the ends of the bolts as shown in FIG. 3. Springs 22 apply a force near the end of projection 8b at a small angle relative to the major axis or plane of the armature when the armature is open and bearing against its stop hereinafter described thereby maintaining pivotal edge 8a of the armature biased against bar in and in its seat. A lever or arm 3d extends from plate 85 at an upward angle and is provided through its free end with an adjustable bolt for engaging actuator as copper or the like and comprises a generally horizontal U-shaped configuration having an upper leg 24a, 26a and a lower leg 24b, 26b. The ends of lower legs 24b and 26b abut against respective terminal members 23 and 3d and are rigidly secured thereto by screws 32 and 34 extending through the respective terminal members to provide electrical connections. Upper legs 24a and 26a are. shorter than lower legs 24!) and 26b and the ends thereof are spaced from terminal members 28 and 30 electrically to insulate the same from the terminal members. Electrical connection of the terminal members to the lower legs of the stationary contacts affords current fiow in directions to aid blowout of the arcs as hereinafter more fully described. Screws 32 and 34 extend through holes in terminal members 28 and 36 into threaded engagement in tapped holes extending axially into lower legs 24b and 26b. Terminal members 23 and 3b have first portions 28a and 30a extending upwardly along the face of panel 2 and second angular portions 28b and 30b extending over the upper edge of panel 2 beyond the rear surface of the panel. Portions 23b and Sill) of the terminal members are provided with suitable electrical connectors 28c and We for connecting electrical conductors thereto.

' Means are provided which are accessible from the front of panel 2 to alford ready removal of the stationary contacts. These means comprise terminal members 23 and 3t) secured to panel 2 by pairs of screws 28d, 28c and Slld, Title extending through holes in the upper and lower ends of portions 28a and 30a of the terminal members and through corresponding holes in the panel into threaded engagement with suitable threaded-sleeve inserts 2a pressed into the panel from the rear face thereof. As will be apparent, screws 28d, 28e and Sild, Lille are accessible from the front face 2b of the panel to facilitate 360 and 38b, 38c extending through the terminal member into threaded engagement in a pair of tapped holes in opposite corner portions thereof.

Molded members 36 and 38 support are blowout magnets of the permanent magnet type for the respective sides of an arcing contact bridge hereinafter described. For this purpose, elongated permanent magnets as and 42 are embedded or molded in members 36 and 38, respectively, and extend transversely through the left-hand end portions of the latter slightly beyond the opposite sides thereof as shown in FIGS. 3, 5 and 9. A pair of nonmagnetic pins .%d are molded in member 36 and a pair of pins 38d are molded in member 38 for supporting removal of the stationary contacts and terminal members when panel 2 is secured to supporting structure.

i The lower portion of the yoke portion of each horizontal U-shaped stationary contact is provided on its outer surface with arecess filled with an arcing contacting member 240, 260 as shown in FIGS. 3 and 5. Immediately below such contacting member, there isprovided a downward projection Zed, 26d having a deeper recess partially filled with a current carrying contacting member 224e, 26c.v These contacting members are comprised of metal such as silver or the, like having good electrical conducting properties. The step-like discontinuity between such contacting members on each stationary contact affords closure and opening of the arcing and current carrying contacts in the proper order as hereinafter described.

, As shown in FIGS. 2, 3 and 5, the windows formed by the U-shaped stationary contacts and the terminal members are filled with molded insulatingmaterial supporting members 36 and 38, respectively. Eachsuch member is provided with a groove 364, 33a around three sides thereof as shown in FIG. 5 and for accommodating the associated stationary contact and is rigidly secured to the associated terminal member by a pair of screws 36!),

magnet pole pieces. The pins of each such pair are arranged parallel to the associated magnet above and belowthe latter and are longer than the associated magnet so that the ends thereof extend beyond the ends of the magnet. A pair of generally rectangular fiat pole pieces 49a and dill) shown in FIG. 5 and each having a pair of holes therein are thereby assembled on the opposite ends of pins Said to engage the flat opposite ends of magnet til. Similar pole pieces 42a and 42b shown in FIGS. 7, 8 and 9 are assembled on pins 38d to engage the ends of magnet 42. The pairs of pole pieces may be held in place by magnetic attraction but theopposite ends of the pairs of pins 364 and 38d may also be riveted over the pairs of pole pieces as shown in FIG. 9 to rigidly secure the same in place. As shown in FIGS. 2 and 7, the pairs of pole pieces 40a, ltlb and 42a, 42b extend on opposite sides of and beyond the respective arcing contacts to form magnetic. air gaps across the latter to blow the electrical arcs when the contacts are opened into arc extinguishing horns hereinafter described. i

As shown in FIGS. 3 and 4, a flat plate 44 of insulating material is rigidly secured to the outer surface of armature 8, plate 44 having a narrower upper end portion 44a extending beyond the upper end of the armature. An insulating sheetd-n having a configuration similar to that of plate 44 isinterposed between plate 44 and armature 8 for purposes hereinafter described. Stud 8e extends through holes 46a and 44b shown in FIG. 4- and is provided with suitable washers 48 and a nut 50 rigidly to secure plate 44 and sheet as to armature 8. A spring pin 8 extends from a hole in armature 8 through a hole in sheet 46 and partway into a hole in plate 44 to prevent rotation thereof on stud 8e. The narrow end portion 44:; of plate 44 is provided with a recess, 440 to reduce the thickness thereof for accommodating an elongated movable current carrying contact bridge 52, the edge of contact bridge 52 being confined against shoulder 44d to maintain the contact bridge transversely on plate 44. The end surfaces of one face of contact bridge 52 are provided with contacting members 52a comprising a metal having good electrical conducting characteristics such as silver or the like for engaging contacting members Mr: and

26e of the stationary contacts to bridge the latter when the electromagnet is energized. As shown in FIGS. 4 and 6, an enlarged-head pin 54- extends through a hole in the narrow portion 44a of plate 44 and a hole in the midportion of contact bridge 52. A helical compression spring 56 surrounds pin 54 and is stopped against a washer 54a surrounding pin 54 and a slotted-end adjust, ing nut 54b threaded on the pin, there being a retaining pin 54c extending through pin 54 intermediate the ends thereof and through the slots to restrain the nut from rotating. Spring 56 resiliently presses contact 52 against- Contact plate 58 is provided with a hole 58!) adjacent the lower end thereof and another hole Ede adjacent one side thereof for freely receiving pins 442 and 44f, respectively, to hold contact plate 58 in registration with its supporting insulating plate 44, pins 44c and 44f being rigidly secured to insulating plate 44. A short bushing 44g surrounds pin 44f to space the lower end of contact plate 58 from insulating plate 44 thereby to afford rocking of the movable arcing contacting members on the stationary contacting members when the armature is actuated and to attain'large surface area engagement between the movable and stationary contacting members when the armature is in its attracted position.

As shown in FIG. 4, arcing contact plate 58 is generally U-shaped or bifurcated at its upper end and the end surfaces of one face of the bifurcated portions have secured thereto contacting members 58d of metal having good electrical conductivity such as silver or the like for engagement with contacting members 24c and 260 to bridge the stationary contacts when the armature is attracted. The midportion of contact plate 5% directly below the slot between the bifurcated portions is provided with a hole Site for freely accommodating pin 5 and spring 56 surrounding the latter. Hole Site is provided with a counter bore 58 for accommodating one end of a helical compression spring 6% surrounding pin 54 and spring 56. The other end of spring d4) is stopped against a stepped washer 5 2d surrounding pin 54 and a slotted-end adjusting nut 54 threaded on the end of the pin, there being a retaining pin 54f extending through pin 54- and through the slots in the nut as shown in FIG. 6 to restrain the nut from turning. Spring 61? resiliently presses contact plate 53 against contact bridge 52 as shown in FIG. 6.

As shown in FIGS. 5 and 9, each molded member, such as members as and 33, is provided at its upper and left-hand end portions on opposite sides thereof with grooves 36% 33c forming a stepped portion for receiving the complementary portion of each arc shield 62, 64 shown in FIG. 7, 9 and 11. Each arc shield 62 and 64 is formed of two complementary portions 62a and 62b,

64a and 64b of insulating material secured to one another by a plurality of bolts 62c and 640, respectively, to form an enclosure closed at the top and partially closed at the bottom and having open ends. One complementary portion 64a of arc shield 64 is shown in FIGS. 10 and 11. Portion 64a is provided with a wall 64d along the upper portion thereof for engagement with a complementary wall on the other portion as shown in FIGS. 1 and 9. A relatively shorter lower wall 642 is provided as shown in FIGS. 10 and 11 for engagement with a complementary lower wall on the other portion as shown in FIG. 1. The aforementioned bolts 64c extend through these upper and lower Walls to clamp the two side portions together. A groove 64 is provided along the right-hand portion as shown in FllG. 11 to provide a reduced portion for receipt in groove 3& in molded member 38 as shown in FIG. 9 to provide the arc shield with close-fitting engagement around the stationary contacts. As shown in FIG. 9, the arc shield 64 fits over molded member 38 between the latter and the associated pole pieces 4.2a and 42b so that the pole pieces extend externally of and along the opposite sides of the respective arc shield. Each 00-. plementary portion of the arc shield is also provided with an angular internal wall such as wall deg shown in FIGS. 10 and 11 to abut the complementary wall on the other portion for reasons hereinafter described.

A clamping bar 65 having a clamping bolt 68 extending therethrough and through mounting panel 2 is provided for cramping the arc shields in. place, bolt 68 extending through the space between the innermost opposed pole pieces 4% and 42a as shown in FIG. 1. Each arc shield is provided with a recess 62h, 64h for accommodating an end of clamping bar 66. The left-hand end portion of each arc shield half portion such as portion 6 64 shown in FIGS. 3 and 10 is provided with a downwardly extending portion 6 2i provided with a curved groove 64 on its inner face for retaining an arc horn member 76, the other side of each diverging arc horn being formed by the curved upper surface of the upper leg 2 in, 26a of each stationary contact. One end of arc horn member 70 is adjacent stationary contact as shown in FIG. 3 and the other end extends externally of the associated arc shield 64 and is provided with an electrical connector such as a bolt 79a or the like. The end of arc horn member '76 adjacent stationary contact 26 is spaced from the stationary contact a shorter distance than the distance between contact members 260 and 58a when the contacts are open as shown in FIG. 3 to improve the transfer of the arc from the contacts to the arc horn when the contacts are opened.

An electrical conductor 72 shown in FIG. 1 connects the external ends of arc horn members 7 t to one another and another electrical conductor 74 connects the external end of one are horn member '70 to bridging contact member 58 as most clearly shown in FIGS. 3 and 4. In this manner, arc horn members 70 are maintained at the same electrical potential as bridging contact member 58.

A pair of bolts 76 are rigidly secured to mounting panel 2 and extend past the opposite sides of armature 8 and the bridging contact assembly. A stopping bar '78 is connected across the ends of these bolts to form a stop for the opening movement of the bridging contacts when the electromagnet is deenergized. As shown in FIG. 3, one of the bolts 76 lies between coil terminals 4a and db to prevent the coil from rotating. The bolts 76 are covered by insulating sleeves 76a to insulate the bolt from the coil terminals.

As shown in FiGS. 2 and 3, mounting panel 2 is provided with counter bores on the rear face thereof to accommodate the ends of the bolts and threaded inserts which are secured thereto. An insulating sheet 80 overlies these counter sunk bolt ends except bolt 63 to insulate the same from one another and from the connector portions 28b and 30b of terminal members 28 and 30. The left-hand end of bolt 68, as shown in FIG. 2, is provided with a removable thumb screw 68a threaded into an axial tapped hole in the end of a hexagonal portion 63b of the bolt to facilitate removal of the arc shields. The right-hand end of bolt 68 is provided with an annular groove for accommodating a retaining ring 680, there being a washer 68d between retaining ring 680 and the bottom of the recess or counter bore in panel 2. The right-hand end of bolt 68 is threaded and extends beyond panel 2 providing means for securing the contactor assembly to a mounting structure or the like. The portion of bolt as immediately adjacent the front surface of panel 2 is hexagonal in shape so that it can be gripped by a wrench and turned into a threaded hole in the mounting structure.

As shown in FIGS' 10 and 11, each half portion of each of the two arc shields such as half portion 64a of arc shield 64 is provided with an angular internal wall 64g. The other half portion of each arc shield such as portions 54!) is provided with a complementary angular wall 64g shown in FIGS. 7 and 8. These two walls 64g and 64g engage one another along their inwardly projecting edges completely to close the interior of the arc shield enclosure throughout the length of these walls. These Walls in each arc shield surround the end and the back of each leg of arcing contact bridge 58 as shown in FIG. 3. These walls prevent the are from flashing between the rear side of the leg of the arcing contact bridge and the rear side of the arc horn member thereby to enhance the transfer of the arc to the arc horn when the arcing contacts are opened.

' Each half portion of each arc shield is provided with an elongated cavity such as cavity 64k shown in FIGS. 3, 7, 10 and 11. As shown in FIGS. 3 and 7, these cavities are in registration with one another and extend along the inner surfaces of the arcshield in the area in registration with the space between the arcing contacting member and the associated stationary contact. More specifically, cavity 64k as shown in FIG. 3 extends in registration with the surface of stationary contact member 260 from the lower end thereof between stationary contact 26 and arc horn member '70 slightly beyond the end of arc horn member 70. The purpose of these cavities 64k is to afford insulating surfaces perpendicular to the direction of the arc. Melted contact material is not likely to be deposited on these perpendicular surfaces and, therefore, these cavities prevent establishment of deposited material conducting paths between the stationary contact and the arcing contact bridge and between the stationary contact and are horn member 769.

As shown in FIGS. 3, 7, 8 and 11, groove tij for are horn member 7% is provided with a stepped upper wall to provide a narrow slot 641 extending along arc horn member 76. This slot is small enough so that the are traveling alongthe horn does not enter therein. This slot is also large enough so that deposited contact material or arc horn material will not bridge the space between arc horn member 749 and the insulating interior Wall of the arc shield; Such bridging of the arc horn member by deposited material on the interior walls of the arc shield might cause the arc to hang up and cause burning of the arc shield. Slot 6d! prevents such burning of the arc shield.

As shown in FIGS; 7 and 9, a narrow slot 64m is provided between the opposite sides of each stationary contact such as contact 26 and the adjacent interior walls of the arc shield. These slots Min-extend throughout the portions of the arc shields where such portions are adjacent the stationary contacts. The size of these slots 64m and their purpose are similar to that described in connection with slots @541 along arc horn member 70.

When operating coil 4 is energized, armature h is names I 8 When coil 4 is deenergized, return springsZZ pivot armature 3 in the counterclockwise direction to open the contacts and to interrupt the electrical connection therethrough at two points in series. When armature 8 starts to pivot, insulating plate engages current carrying contact bridge 52 to move the latter in the left-hand direction in FIG. 3 and to disengage contact members 5211 from stationary contacting members 2% and 26e to interrupt the current carrying connection. As armature 8 starts to pivot as aforesaid, spring 56 maintains the current carrying contacts closed while the gap between insulating plate 4-4 and contact bridge 52 closes. insulating plate 44 first engages contact bridge 52 at the upper portion thereof as seen in FIG. 3 to impart to contact bridge 52 a counterclockwise rocking movement. This tends to break any weld between the current carrying contacting members. As the armature pivots further following opening of the current carrying contacts, spring 60 maintains the arcing I contacting members closed as the gap between contact bridge 52 and contact plate 53 closes. This pivoting of the armature also causes pivot pin 44-) to move in the left-hand direction in FIG. 3 thereby to impart a clockwise rocking movement to the arcing contacting members 58d. This tends to' break any weld between the movable and stationary contacting members. After contact bridge 52 engages contact plate 58, the arcing contacting mem hers open in response to the complete pivoting of the armature in'the opening direction. During the clockwise and counterclockwise pivoting of the armature, springs 22 apply a force on the end of arm 8b in a direction tending to maintain pivotal edge tin of the armature in its seat attracted to the end of core 6 having washer 6a secured I thereto. Armature 3- pivots on edge 8a thereof in the clockwise direction to cause compression of return springs 22. The magnetic attraction of armature 8 maintains pivot 8a thereof against bar 16. Arm 8d actuates switch 2%. Armature 8 carries the assembly comprising insulat contacts 24 and 26, respectively, to bridge the stationary' contacts. As the armature pivots further, current carrying contact bridge 52 separates from arcing contact plate 58 and spring 6b is compressed. Spring 56, however, maintains current carrying contact bridge 52 in engagement with insulating plate 44 to move with the latter. It will be apparent that during such further pivoting of the armature, arcing contact plate 58 pivots on pin 44 relative to insulating plate 44 and that the pivot point, that is, pin 44 of arcing contact plate 58 moves toward the right in FIG. 3. This imparts a rocking movement to contacting members 58a to rock the same into large area surface engagement with stationary contacting members 24c and 26c. Thereafter, contacting members 52a of current carrying contact bridge 52 engage stationary contacting members 24c and 26a to bridge the stationary contacts. Further pivoting of the armature into engagement with washer 6a on the end of core 6 causes spring 56 to be compressed as current carrying contact bridge 52 separates from insulating plate 44. Such separation of contact bridge 52 and plate 44 allows contacting members 52a to settle into large area surface engagement with stationary contacting members 24c and 26c. Also, spring 56 maintains sufi'icient contact pressure therebetween to establish a good electrical connection. When spring 56 is compressed as aforestated, spring 60 is compressed further to maintain sufiicient contact pressure between the arcing contacting members.

against bar in.

Permanent magnets sit) and 4-2 are polarized in opposite directions so that the arcs between the respective stationary contacts and the legs of arcing contact plate 58 are blown in a direction away from the current carrying contacts and into the arc horns. As the arcing contacting members 58d separate fromthe stationary contacts, the arcs drawn therebetween are blown upwardly in FIGS. 1, 2 and 3 by the magnetic fields produced by the permanent magnets 4t and d2 between'the pole pieces of the respective pairs thereof. The direction in which the arcs. are moved is expressed by Flemings left-hand rule. According to this rule, if the forefinger is pointed in the direction of the tiux between the pole pieces and the middle linger is pointed in the direction of the current in the arc, the thumb will point in the direction in which the arc will move. Assuming that in FIG. 3, the current flows downward in terminal 34) and in the left-hand direction in the lower leg 26!) of the stationary contact and across the gap into arcing contacting member 53d and out through the other terminal, then permanent magnet 42 must have a polarity of a north pole at its left end and a south pole at its right end as viewed in FIG. 1 or a south pole at itsnear end and a north pole at its far end in FIG. 3. This polarity will cause the magnetic flux which passes. from north pole piece 42a transversely of the arcing contact gap to south pole piece 42b to move the are unwardly. As the arc moves upwardly, Wall 64g in the arc shield prevents the are from striking between arcing contact plate 55% and are horn member '70. As shown in FIG. 3, the right-hand end of arc horn member This nearer sta tionary contact 26 than is arcing contacting member 53d when fully open. This difference in distance between arc horn member 7t and stationary contact 26 relative to the distance between contacting members 58d and 2-60 enhances transfer of the arc to the arc horn. The arc then moves outwardly along the upper surface of arc horn member 70 and the upper surface of stationary contact 26 until it ruptures and is extinguished. Upper legs 24a and 26a of stationary contacts 24 and 26, respectively, are shorter than the lower legs 24b and 26b to provide an insulating air gap between such upper legs and the respectively associated terminal members 28 and 3%. This air gap tends to prevent the arcs from running onto the terminal members.

The terminal members are arranged and constructed so that the currents flowing therein increase the magnetic force of the blowout magnets rather than decrease it. For example, current flowing downwardly in terminal member 30 in FIG. 3 develops magnetic lines of force passing in the clockwise direction around the terminal member when viewed from above according to the Ampere rule. As permanent magnet 42 is polarized with a south pole at its near end and a north at its far end in FIG. 3 and the magnetic lines of force in a permanent magnet pass therethrough from the south end toward the north end, it will be apparent that the lines of force developed by the current in the terminal member are in the same direction and, therefore, tend to increase the blowout effect.

As will be apparent, conductor 72 electrically connects arc horn members 7t) to maintain them at the same potential. Also, conductor 74 connects arc horn members 76 to arcing contact plate 58 to maintain them at the same potential thereby to facilitate transfer of the arcs from the arcing contacts to the arc horns under the action of the blowout devices. Movable current carrying contact 52 is maintained in electrical connection with movable arcing contact plate 53 through springs 56 and 60 and bolt 54.

As will be apparent, use of the arcing contacts which close first and open last prevents arc damage to the current carrying contacts. The bridging contact construction enables the contactor to control larger currents and voltages. This is for the reason that the electrical connection is interrupted in two places simultaneously. As the circuit is interrupted in two places, the voltage across the opening contacts on each side of the bridging contact will be only one-half of what it would be across a single interrupting contact.

The terminal members 300 are widely spaced from other metallic members of the contactor to insulate the same from one another. The arc shields 62 and 64 are readily removable by removing thumb screw 68a and clamping member 66 and conductor 74. Among other things, the stationary contacts 24 and 26 are readily removable from the front as seen in FIG. 1 without removing the contactor base 2 from its mounting structure to which it may be secured by the threaded end of bolt 68. To remove stationary contact 26, it is only necessary to remove screws 30d and 3% which are accessible from the front. This permits removal of the assembly comprising terminal member 3%, contact 26, molded member 38, magnet 42 and pole pieces 42a and 42b. This facilitates replacement of the stationary contacts 24 and 26. The threaded nuts 54b and 54a on bolt 54 afford easy adjustment of the forces of springs 56 and of). These nuts are provided with suitable slots to accommodate locking pins 54c and 54 to lock the nuts in adjusted positions. Use of alnico permanent magnets 4t and 42 affords strong magnetic fields for extinguishing the arcs. Cavity 64k prevents deposited contact material from establishing an electrical path between the contacts or between the portions of the arc horn. And slots MI and 64m tend to prevent the arcs from burning the arc shields.

While the apparatus and structures hereinbefore described are effectively adapted to fulfill the objects stated, it is to be understood that I do not intend to confine my invention to the particular preferred embodiment of electric switch having arc extinguishing means disclosed, inasmuch as it is susceptible of various modifications with out departing from the scope of the appended claims.

I claim:

1. In an electromagnetic switch having a mounting panel of electrically insulating material adapted to be mounted so that its rear surface bears against a supporting structure, stationary contacts mounted on the front surface of said panel, movable contacts normally separated from said stationary contacts, and means comprising an electromagnetic actuator for moving said movable con- 10 tacts into engagement with said stationary contacts and restoring means for returning said movable contacts out of engagement with said stationary contacts, the improvement comprising:

means mounting said stationary contacts on said mounting panel to afford access from the front of said panel for ready removal thereof comprising:

a plurality of electrical connector members, there being one such connector member for each stationary contact;

each said connector member having a first portion lying along the front face of said panel and an angular portion extending over an edge of said panel and beyond the rear surface thereof providing a terminal which is readily accessible for connection to an external circuit when said panel is mounted on its supporting structure;

means mechanically and electrically connecting each stationary contact on said first portion of its associated connector member to be supported by the latter and to afford connection thereof to an external circuit;

and readily removable means accessible from the front of said panel for rigidly securing said first portion of each connector member to said panel whereby said connector members and the respective stationary contacts secured thereto are readily removable from the front side of said panel while the latter remains mounted in its supporting structure.

2. The invention defined in claim 1, wherein said rea ily removable means comprises:

a pair of securing members for each said connector member, the securing members of each pair thereof rigidly securing said first portion of the respective connector member to said panel at points on opposite sides of the associated stationary contact.

3. The invention defined in claim 1, wherein said electromagnetic actuator comprises:

an elongated magnetizable core;

an energizing coil surrounding said core;

'a movable armature arranged to be attracted by the magnetic field of said core when said coil is energized to move said movable contacts;

means rigidly securing said core at one end to said panel so that it extends forwardly from the front surface thereof;

and readily removable means secured to the forwardly projecting end of said core for retaining said coil on said core and being accessible from the front of said panel whereby said coil is readily removable from said core while said panel and said core secured thereto remain mounted on the supporting structure.

4. In an electric switch having a mounting panel, two spaced apart connector members removably mounted on said panel, two stationary contacts secured to the respective connector members, movable bridging contact means for engaging said stationary contacts electrically to connect and disconnect the same, and an electromagnetic actuator for actuating said movable bridging contact means, said actuator comprising a magnetic core mounted at one end to the front surface of said panel, a coil surrounding said core, readily removable means secured on the other end of said core for maintaining said coil on said core and being accessible from the front of said panel for removing said coil, a pivoted armature for attraction to said other end of said core when said coil is energized, and means mounted on said armature for supporting said movable bridging contact means and comprising means for resiliently biasing said movable bridging contact means against said supporting means, and threaded means for adjusting the magnitude of said resilient bias thereby to afford fine adjustment of the contact pressure.

5. In an electric switch having a mounting panel, two spaced apart connector members removably mounted on army/e 1 l said panel, two stationary contacts secured to the respective connector members, movable bridging contact means for engaging said stationary contacts electrically to connect and disconnect the same, and an electromagnetic actuator for actuating said movable bridging contact means, said actuator comprising:

a magnetic core mounted at one end to the front surface of said panel; a coil surrounding said core; 7 readily removable means secured on the other end of said core for maintaining said coil on said core; a pivoted armature for attraction to said other end of said core when said coil is energized; means mounted on said armature for supporting said movable bridging contact means and comprising means for resiliently biasing said movable bridging contact means against said supporting means; threaded means for adjusting said resilient bias thereby to adjust the contact pressure; I said armature being provided with an elongated angular supporting pivot; and a sealing member engaging said armature thereacross adjacent said pivot to prevent entry of deleteriousmaterial therein. 6. In an electric switch having a mounting panel, two spaced apart connector members removably mounted on said panel, two stationary contacts secured to the respective connector members, movable bridging contact means for engaging said stationary contacts electrically to connect and disconnect the same, and an electromagnetic actuator for actuating said movable bridging contact means, said actuator comprising:

a magnetic core mounted at one end to the front surface of said panel; a coil surrounding said core; readily removable means secured to the other end of said core for maintaining said coil on said core; a pivoted armature for attraction to said other end of said core when said coil is energized; means mounted on said armature for supporting said movable bridging contact means and comprising means for resiliently biasing said movable bridging contact means aga-inst'said supporting means; threaded means for adjusting said resilient bias thereby to adjust the contact pressure; a spring return means for pivoting said armature to its normal position when said coil is deenergized;

and a stop for said armature comprising: a pair of elongated members secured to said panel an extending from the front surface thereof on opposite sides of said coil and armature;

1 12 a cross bar connected to said elongated members forming a stop for said armature; said coil being provided with a pair of spaced terminal members for connection thereof to an energizingcircuit; one of said elongated members extending between said coil terminal members to restrict the coil from rotating on said core; and an insulating sleeve on said one elongated member for insulating the latter from said terminal members. 7. In an electric switch having a mounting panel, two stationary contacts mounted in spaced apart relation on the front surface of said panel, movable bridging contact means for engaging said stationary contacts electrically to connect and disconnect the same, a supporting member, means mounting said bridging contact means on said supporting member, an electromagnetic actuator for actuating said supporting member to move said bridging contact means, said actuator comprising a magnetic core mounted on the front surface of said panel, a coil surrounding said core and a pivoted armature having said supporting member secured thereto, the improvement comprising means mounting said stationary contacts and said coilon said panel to afford access from the front of said panel for removal thereof comprising an electrical connector memher for each said stationary contact, means mechanically and electrically connecting each stationarycontact to its associated connector member, means accessible from the front of said panel securing each said connector member to said panel, each said connectorrnember having a portion lying along the front surface of said panel and a portion extending over an edge of said panel and beyond the rear surface thereof providing a terminal for connection to an external circuit, means rigidly securing said core at one end to said panel so that it extends from the front surface thereof, and readily removable means secured to the projecting end of said core for retaining said coil on said core.

References slit-ed in the file of this patent UNITED STATES PATENTS 1,742,109 Weber Dec. 31, 1929 1,780,684 Owens Nov. 4, 1930 2,304,972 Van Valkenburg et a1. Dec. 15, 1942 2,394,090 McFarland Feb. 5, 1946 2,687,502 Furnas Aug. 24,1954 2,855,548 White Oct. 7, 1958 3,035,137 Furnas etal; May 15, 1962 FOREIGN PATENTS 446,743 Canada Feb. 17, 1948 534,768 Great Britain Mar. 17, 1941 

1. IN A ELECTROMAGNETIC SWITCH HAVING A MOUNTING PANEL OF ELECTRICALLY INSULATING MATERIAL ADAPTED TO BE MOUNTED SO THAT ITS REAR SURFACE BEARS AGAINST A SUPPORTING STRUCTURE, STATIONARY CONTACTS MOUNTED ON THE FRONT SURFACE OF SAID PANEL, MOVABLE CONTACTS NORMALLY SEPARATED FROM SAID STATIONARY CONTACTS, AND MEANS COMPRISING AN ELECTROMAGNETIC ACTUATOR FOR MOVING SAID MOVABLE CONTACTS INTO ENGAGEMENT WITH SAID STATIONARY CONTACTS AND RESTORING MEANS FOR RETURNING SAID MOVABLE CONTACTS OUT OF ENGAGEMENT WITH SAID STATIONARY CONTACTS, THE IMPROVEMENT COMPRISING: MEANS MOUNTING SAID STATIONARY CONTACTS ON SAID MOUNTING PANEL TO AFFORD ACCESS FROM THE FRONT OF SAID PANEL FOR READY REMOVAL THEREOF COMPRISING: A PLURALITY OF ELECTRICAL CONNECTOR MEMBERS, THERE BEING ONE SUCH CONNECTOR MEMBER FOR EACH STATIONARY CONTACT; EACH SAID CONNECTOR MEMBER HAVING A FIRST PORTION LYING ALONG THE FRONT FACE OF SAID PANEL AND AN ANGULAR PORTION EXTENDING OVER AN EDGE OF SAID PANEL AND BEYOND THE REAR SURFACE THEREOF PROVIDING A TERMINAL WHICH IS READILY ACCESSIBLE FOR CONNECTION TO AN EXTERNAL CIRCUIT WHEN SAID PANEL IS MOUNTED ON ITS SUPPORTING STRUCTURE; MEANS MECHANICALLY AND ELECTRICALLY CONNECTING EACH STATIONARY CONTACT ON SAID FIRST PORTION OF ITS ASSOCIATED CONNECTOR MEMBER TO BE SUPPORTED BY THE LATTER AND TO AFFORD CONNECTION THEREOF TO AN EXTERNAL CIRCUIT; AND READILY REMOVABLE MEANS ACCESSIBLE FROM THE FRONT OF SAID PANEL FOR RIGIDLY SECURING SAID FIRST PORTION OF EACH CONNECTOR MEMBER TO SAID PANEL WHEREBY SAID CONNECTOR MEMBERS AND THE RESPECTIVE STATIONARY CONTACTS SECURED THERETO ARE READILY REMOVABLE FROM THE FRONT SIDE OF SAID PANEL WHILE THE LATTER REMAINS MOUNTED IN ITS SUPPORTING STRUCTURE. 